1. Field of the Invention
The present invention generally relates to network services, and more particularly to providing interdomain services for network reliability.
2. Brief Description of the Related Art
Reliability is a major concern in Internet Protocol (IP) networks. As the Internet becomes a critical infrastructural component of the global information-based society, the availability and resilience of the Internet under failures can have significant global and social effects.
Various techniques have been developed to improve communication network reliability. For example, in the past, networks have relied on link layer techniques, such as SONET rings, to protect networks against failures. More recently, due to the relatively high cost of SONET protection and the lower cost and improved flexibility of IP, networks now utilize the IP layer to handle failures.
In some implementations, restoration techniques have been used in the IP layer for rerouting data under potential failures. A potential drawback of these restoration techniques is their relatively slow response time, which may not be able to meet the requirements of some mission-critical applications (e.g., VPN networks carrying VoIP traffic). The restoration techniques also can include MPLS-based protection techniques that pre-compute rerouting paths and quickly reroute traffic upon failure detection. The two basic protection mechanisms are link protection (i.e., fast rerouting (FRR)), and path protection. In FRR, a detour around a failed link is created. In path protection, the sources of flows using a failed link are identified and rerouted to avoid the failed link. An advantage of path protection is that, since alternate paths are computed for each source, it can avoid potential bottlenecks around the head end of a failed link, and thus achieve better rerouting performance.
Although these techniques have enhanced IP network reliability, they generally require significant investments. Accordingly, a major challenge remains in obtaining redundancy in IP networks at a reasonable cost. As used herein, the term redundancy refers to both the diversity of physical connectivity and the over-provisioning of bandwidth to carry traffic originally passing through any failed equipment. In addition, with the cost of over-provisioning and, in particular, the expenses to obtain rights-of-way to install alternative paths (e.g., along natural gas pipelines, highways or railways), many IP networks, in particular Internet Service Provider (ISP) networks, face the challenge of adding redundancy in a cost-effective way to stay competitive in the highly competitive ISP market.